Furnace ladling apparatus and crucible

ABSTRACT

A furnace ladling apparatus comprises a crucible mounted in a furnace and having an inlet passage and delivery tube disposed within the crucible adjacent a side wall thereof. A delivery spout extends from an opening communicating with the delivery tube in the upper end of the crucible. A pair of reference electrodes are spaced along one side of the passage in the delivery spout so as to be responsive to the level of molten metal in the spout. Shot timer means are connected to the reference electrodes so that the timer is actuated when the molten metal reaches the reference electrodes in the delivery spout so as to provide a predetermined amount of metal.

Apr. 8, 1975 I United States Patent Lauersdorf [54] FURNACE LADUNGAPPARATUS AND FOREIGN PATENTS OR APPLICATIONS mmm 00" dd." 0 .m.m y 43.mmm nne UUG 057 765 9 99 HHH 2000 994 476 6 5 05 n t m ch r o d S a L He n. me E Dw M l m C t n W e v C m J 7 .l

Assignee: Sola Basic Industries, Inc.,

Primary E.\'ammer-Gerald A. Dost Milwaukee Wm Attorney. Agent, orFirm-Smythe & Moore Mar. 15, 1973 [22] Filed:

[57] ABSTRACT A furnace ladling apparatus comprises a crucible Appl.No.: 341,736

mounted in a furnace and having an inlet passage and delivery tubedisposed within the crucible adjacent a side wall thereof. A deliveryspout extends from an opening communicating with the delivery tube inthe 94 bn33 M 8 6 3 26 a 9 '1 3 "l N N 2 n .9 2 "0 a m B u we 6 n 0 6 U2 n u 3 ""00 m m m 7 m5 r wk S5 .l f C M d6 Sol fl UmF mum 555 upper endof the crucible. A pair of reference electrodes are spaced along oneside of the passage in the 222/399, DlG. l2

delivery spout so as to be responsive to the level of molten metal inthe spout. Shot timer means are con- [56] References Cited UNITED STATESPATE NTS nected to the reference electrodes so that the timer isactuated when the molten metal reaches the reference electrodes in thedelivery spout so as to provide a predetermined amount of metal.

'2 Claims, 5 Drawing Figures Tornberg........... Morris et al. Schwartzet a1. 960

L e m 6 HL .llrilliil IR PRESSURE 07 @QMQQQEQ VQQQE FURNACE LADLINGAPPARATUS AND CRUCIBLE The present invention relates to a furnaceladling apparatus and, more particularly, to a crucible for theapparatus having a delivery spout with reference level means therein.

A number of different furnace ladling devices have been proposed forforcing molten metal from the chamber of a melting furnace to a desiredpoint of use, such as to a die-casting machine. Such devices have beengenerally in the form of a crucible which has a discharge tube externalto the main body of the crucible and extending upwardly to a point abovethe molten metal in the chamber and discharging the metal adjacent toone side of the chamber. When used in conjunction with a die-castingmachine, measured shots or amounts of molten metal are periodicallydischarged. Examples of such are seen in US. Pat. Nos. 2,846,740,3,050,794, 3,191,247 and 3,229,337.

When the apparatus is so constructed that the molten metal may stand inthe discharge tube above the level of molten metal in the chamberbetween successive shots, there is a tendency for the metal in the upperpart of the discharge tube to freeze or to cool to a mushy consistencyshould the duration between successive shots become too great. If thereare any delays due to difficulty with the die-casting machine or for anyother reason, a freezing or partial freezing of the metal in thedischarge tube may occur which in turn makes it difficult to restart theoperation.

One of the objects of the present invention is to provide an improvedcrucible for a furnace ladling apparatus.

Another of the objects of the invention is to provide an improved devicefor dispensing a predetermined amount of molten metal from the dischargespout.

Another object of the invention is to eliminate the necessity ofmodifying the furnace body for a discharge tube.

According to one aspect of the present invention, a furnace ladlingapparatus has a hollow chamber to contain molten metal and a crucible ispositioned in the chamber. The crucible comprises means for defining amolten metal inlet and it also has a delivery tube with the upper end ofthe tube terminating above the normal level of molten metal in thechamber. A delivery spout is connected to the delivery tube open end andthe spout includes means responsive to the level of molten metaltherein. The metal inlet and delivery tube both comprise verticallyextending passages which are positioned adjacent the inner face of thewall of the crucible.

Other objects, advantages and features of the present invention willbecome apparent from the accompanying description and drawings, whichare merely exemplary.

In the drawings:

FIG. 1 is a vertical sectional view through a portion of a furnaceladling apparatus and through a crucible mounted within the furnace;

FIG. 2 is a top plan view of one form of crucible showing thearrangement of passages therein;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along the line 44 of FIG. 2; and

FIG. 5 is a schematic diagram'showing one form of an electrical controlcircuit including a shot size'timer and reference electrodes actuatingthe timer.

Proceeding next to the drawingswherein like reference symbols indicatethe same parts throughout the various views, a specific embodiment ofthe present in vention will be described in detail.

As may be seen in FIG. 1, there is shown a furnace indicated generallyat 10 which may be any desired type of metal melting or holding furnaceformed of refractory material and defining an inner chamber 11containing molten metal 12. In operation of the furnace, it is generallycontemplated that the level of the metal therein will vary from level 12to a lower minimum level which will not fall below the bottom end of acrucible 13 mounted within the furnace.

The upper end of the crucible is constructed with a flange 14 whichrests upon a crucible cradle 15 mounted on the top 16 of the furnace andsecured in position by bolt means 17. The crucible is closed by aclean-out lid 18 to which is connected nipple 19. The lid 18 also has anopening 20 to receive the upper end of delivery tube 21 whose lower endis open at 22 and extends below the normal level of the molten metalwithin the furnace.

The crucible 13 can be made of a suitable refractory. One refractory isa clay-free mixture of silicon carbide and zircon which isthixotropically cast in the mold and then fired or sintered. Theparticle sizes of silicon carbide and zircon are chosen to provide thedesired characteristics. In addition, suitable water retention anddispersing agents can be added to the mixture.

Also mounted within the crucible is a vertically extending inlet tube 23(FIG. 4) whose lower or inlet end 24 opens at the bottom of the crucibleand whose upper end 25 opens into the crucible space below the topthereof.

As can be best seen in FIGS. 2 to 4, both of the delivery and inlettubes 21 and 23 can be positioned side by side within the crucibleagainst an inner face of the cylindrical wall of the crucible and may beintegrally formed with the wall of the crucible, as shown in thedrawings. Thus, the inlet tube and delivery tube are integral componentsof the crucible, and their position within the crucible enables themolten metal within the crucible to prevent excessive heat loss of themetal in these tubes.

The upper end of the delivery tube 21 is indicated at 26 and isconnected to an opening 27 (FIG. 1) in a delivery spout 28 which has apassage 29 with an upwardly inclined bottom surface 30 extending to adischarge opening 31 below which can be positioned a shot cylinder 32 asis known in the art. The function of the delivery spout 28 is totransfer molten metal from the crucible to the shot well of adie-casting machine (not shown). Positioned on sides of the deliveryspout are two spaced reference electrodes 33 and 34. Metal entering thedelivery spout through the opening 27 continues to rise until the metalshorts out across both electrodes, thereby acting as a switch to startthe timing of the shot size timer, which may be seen in the controlcircuit of FIG. 5. As soon as the shot is completed, the metal in thedelivery spout runs back into the crucible to clear the referenceelectrodes.

Electrode 33, which is closer to the discharge opening 31, is positionedat the horizontal level of this opening so that this electrode will becontacted by the metal at the precisemoment that the metal begins toflow through the opening 31 into the shot cylinder so as to start thetiming cycle.,Electrodes 33 and 34 may comprise conventional sparkplugs, and the reference level detector may operate at a low voltage,such as 12 volts. As known in the art, nipple l9 communicating with theupper end of the crucible 13 is connected to a suitable compressed airsupply which is used to introduce a pressure into the crucible to forcethe metal through the delivery tube and out through the delivery spout.It also is possible to alternately connect a vacuum to the crucible.

The size of the shot in the die-casting machine is determined by thesetting of the shot size timer and the pump flow rate valve. Once theproper flow rate is established, the size of the shot can be changed byvarying the setting of the shot size timer. Once the timer has been setto the desired time, the furnace will continue to deliver an identicalamount of metal with each shot.

Referring now to one form of circuit which can be used, such as seen inFIG. 5, line voltage is applied at 35 to the circuit. The operation canbe started by closing start switch 36 which will energize the primary ofstep-down transformer 37. When the start switch 36 is actuated, relay 38will be closed which is a lock-in arrangement andwill close contacts 39.In case there is a power failure, the circuit will open. The shot size 1timer, which can be a conventional timer means, is indicated as beingwithin the dot-dashed lines 44. Switch 45 is an interlocking circuitwhich indicates that the shot well is cleared so as not to pump onebatch of metal upon another. When switch 46, which is a limit switch onthe die-casting machine, closes, the relay 41 will be activated so thatthe pumping action then is actually started. Relay 42 is a backup timer.As metal comes into passage 29, it will close the circuit across theelectrodes 33 and 34 which will result in the secondary of transformer37 energizing relay 47. When relay 47 is energized, contacts 48 willclose to energize the shot size timer 44. When the shot size timer timesout, it operates to open switch 49.

The proper timer setting can be determined for each size shot inaccordance with procedures well known in the art.

In the form shown in FIG. 1, the height of top 25 is so related to thelevel of the metal that flow into the crucible will be by gravity. Ifthe height of the top end 25 is above the normal level of molten metalin the furnace 10, then a vacuum can be applied to the chamber 50through opening 19.

Thus, it can be seen that the present invention provides for theautomatic energization of the shot size timer in response to apredetermined level of liquid in the delivery spout. The level of liquidmay coincide with the initial flow of liquid through the delivery spoutso that the timer will be energized at the beginning of the flow ofmetal for a shot. In addition, there is disclosed a crucible where theinlet and delivery tubes are disposed completely within the outline ofthe crucible whereby freezing of metal which may be in the tubes is,

largely eliminated.

It will be understood that changes in various details of constructionand arrangement of parts may be made without departing from the spiritof the invention except as defined in the appended claims.

What is claimed is:

1. In a furnace ladling apparatus, the combination including a hollowchamber to contain molten metal, a crucible in said chamber, means insaid crucible and integral therewith defining a molten metal inlettherein, a delivery tube within said crucible and integral therewithhaving its upper end terminating above the normal level of molten metalin the chamber, a delivery spout in fixed position on said crucible andcommunicating with the delivery tube upper end, and means in saiddelivery spout responsive to the level of molten metal therein, saidmetal inlet and delivery tubes comprising means defining verticallyextending passages within the crucible, the vertical passages beingpositioned adjacent each other and to the inner face of the side wall ofsaid crucible.

2. A crucible for a furnace ladling apparatus comprising a substantiallycylindrical body having top and bottom ends adapted to be placed in ametal holding furnace, means in said crucible defining a first integralvertically extending passage opening at the bottom of the crucible for amolten metal inlet, means in said crucible defining a second integralvertically extending passage having its upper end terminating above thenormal level of molten metal within the furnace for the delivery ofmolten metal from the crucible, said passage defining means beingagainst the inner face of the crucible body wall, and said inlet passageand said delivery tube are positioned adjacent each other against theinner face of the cylindrical wall of the crucible.

1. In a furnace ladling apparatus, the combination including a hollowchamber to contain molten metal, a crucible in said chamber, means insaid crucible and integral therewith defining a molten metal inlettherein, a delivery tube within said crucible and integral therewithhaving its upper end terminating above the normal level of molten metalin the chamber, a delivery spout in fixed position on said crucible andcommunicating with the delivery tube upper end, and means in saiddelivery spout responsive to the level of molten metal therein, saidmetal inlet and delivery tubes comprising means defining verticallyextending passages within the crucible, the vertical passages beingpositioned adjacent each other and to the inner face of the side wall ofsaid crucible.
 2. A crucible for a furnace ladling apparatus comprisinga substantially cylindrical body having top and bottom ends adapted tobe placed in a metal holding furnace, means in said crucible defining afirst integral vertically extending passage opening at the bottom of thecrucible for a molten metal inlet, means in said crucible defining asecond integral vertically extending passage having its upper endterminating above the normal level of molten metal within the furnacefor the delivery of molten metal from the crucible, said passagedefining means being against the inner face of the crucible body wall,and said inlet passage and said delivery tube are positioned adjacenteach other against the inner face of the cylindrical wall of thecrucible.